This is a per-client TACACSPLUS key which is used as the
TACACS+ key. EncryptedTACACSPLUSKey is in encrypted format and is
preferred over TACACSPLUSKey. Do not use it with RADIUS requests. For more
information, see
Section 3.119.1. Key.
EncryptedTACACSPLUSKey
is currently experimental and will be fully documented later.